Oar



July 26, l938. w. MEIENREIS OAR Filed May 2, 1936 In Venfor:

Patented July 26, 1938 UNITED STATES PATENT oFFicE Application May 2, 1936, Serial No. 77,604 In Germany May 6, 1935 Claims.

When pulling an car through water, a pressure zone will be produced on one side of the blade and a suction zone on the other side thereof. Both zones are of importance with regard to 5 the effect of the oar, since they produce resistance against the movement of the car blade through the water. The higher the resistance per unit area the more favourable will be the rowing effect for the propulsion of the boat.

An car is generally moved through the water so that the upper or top-edge of the blade is approximately on a level with the surface of the Water. It will then be seen that when moving the oar through the water, the surface of the water behind the blade (in the direction of the movement) will be lowered. A hollow space will be formed which, after the oar has been pulled through, will be filled by an eddy. The'hollow space and eddy must necessarily affect the effect of the car and the prevention thereof consequently results in improving the efficiency of the car. In the case of the ordinary oar the efficiency of the car will be lessened when the oarsmans efforts are increased, because the hollow space behind the car, will be enlarge-d. (In connection with a ships propeller the phenomenon of so-called cavitation will be simultaneously accompanied by a sudden decrease in the efliciency of the propeller.)

It is an object of the present invention to obviate the formation of the hollow space and thus also of the eddy resulting therefrom, by adding a lobe to the suction side of the blade of the oar.

It is a further object of the invention to provide an oar wherein the pressure side of the oarblade is similar to that of an ordinary oar-blade, while the suction side is provided with a lobe for preventing the formation of a hollow space and of an eddy on the suction side of the car when pulling the latter through the water. According to the invention the lobe is so arranged and shaped that the cross-section of the oar-blade resembles in shape a reversed L, one shank of which is in a horizontal position and the other shank of which is in a perpendicular position when pulling the oar-blade through the water.

The present invention is illustrated, by way of example in the accompanying drawing, in which Fig. 1 represents a view of the rear of the blade of the oar in elevation.

Fig. 2 shows a plan view of the car.

Figures 3 and 4 are crosssections of the oar taken on lines III-III and IV-IV of Figure 1.

In accordance with the present invention the suction or rear side of the blade I is provided space is prevented.

along its upper edge with a streamline or otherwise suitably shaped lobe 3 the underside of which curves downwardly into the blade. When using the oar the water will rise up along the blade in such a manner, that the formation of a hollow 5 The lobe partially replaces the water on the suction side of the oar-blade and thereby prevents the car from dropping, which otherwise would take place on account of the hollow space, and also prevents the for- 10 mation of the hollow space. In consequence thereof the water will flow off on the suction side of the blade without forming an eddy effect so that the useful suction effect will not be decreased. Thissuction effect, on the contrary, 15 will be increased in View of the fact that on the suction side of the car there will be water only and no hollow space.

What I claim is:-

1. An oar comprising in combination a shank, 20 an oar-blade and means on the upper edge of the oar-blade for preventing the formation of a funnel-shapedhollow space and an eddy on the suction side of the car when pulling the latter through the water. 25

2. An oar comprising in combination a shank, an oar-blade and means on the upper edge of the oar-blade for preventing the formation of a funnel-shaped hollow space and an eddy on the suction side of the oar when pulling the latter through the water, the said means consisting of a lobe on the suction side of the oar-blade.

3. An oar comprising in combination a shank, an oar-blade and means for preventing the for mation of a funnel-shaped hollow space and an 35 eddy on the suction side of the oar when pulling the latter through the Water, the said means consisting of a lobe on the suction side of the carblade, said lobe being sodisposed and shaped that the cross-section of the oar-blade resembles 40 in shape a reversed L, one shank of which being in a horizontal position and the other shank in a perpendicular position when pulling the oarblade through the water.

4. An oar comprising in combination a shank, an oar-blade and means for preventing the formation of a funnel-shaped hollow space and an eddy on the suction side of the oar when pulling the latter through the water, the said means consisting of a lobe on the suction side of the oar-blade, said lobe being so disposed and shaped that the cross-section of the oar-blade resembles in shape a reversed L, one shank of which being in a horizontal position and the other shank in a perpendicular position when pulling the oarblade through the water, the said horizontal shank being of streamline shape and merging into the perpendicular shank in a curve.

5. An oar comprising in combination a shank, an oar-blade and. means for preventing the formation of a funnel-shaped hollow space and an eddy on the suction side of the oar when pulling the latter through the Water, the said means 'consisting of a lobe on the suction side of the oar-blade, said lobe being so disposed and shaped that the cross-section of the oar-blade resembles in shape a reversed L, one shank of which being in a horizontal position and the other shank in a perpendicular position when pulling the oarblade through the Water, the said horizontal shank being of streamline shape and merging into the perpendicular shank in a curve and, furthermore, the shanks of the reversed L tapering from the outer end of the oar-blade towards the inner end of the oar-blade.

WALTHER MEIENREIS. 

